Power supply unit



FIG. 1 is a front elevation view of a power supply unit showing our new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a side elevation view thereof;

FIG. 4 is an opposite side elevation view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines shown represent unclaimed subject matter and form no part of the claimed design. 

The ornamental design for a power supply unit, as shown and described. 